Hi Richard, very much appreciate your involvement.

“My job is just to try and advise them on the possible consequences of different courses of action to the best of our current understanding, so they can make decisions which are as informed as possible. In many cases this does of course come down to hedging their bets. As I believe I have said before, if you don't like the policy, tell your MP not me!”

Eloquently said Richard and many, many thanks for your involvement here. However I have a problem with your comment above and it is a problem to which I do not profess to have an obvious solution.

You profess to try to “advise them on the possible consequences of different courses of action to the best of our current understanding”

Then “In many cases this does of course come down to hedging their bets”

What exactly are these “bets”? Are they scientific or political? If they are “their” bets then I take it that they are political?

In what position are you as a scientist capable of appreciating their ability to assess such bets?

Next “if you don't like the policy, tell your MP not me!” At what stage, and I am very sorry for the way that this may sound, do you stand up to be accounted for if the “political hedged bets” bastardise your science?

If you are going to let them “hedge their bets” then it is your obligation as a scientist to quantify the potential errors of the risks that they are taking.

At present I find myself asking questions of scientists and being referred to politicians and when I ask politicians I am referred to scientists.

There are a few examples of such in recent history, of which I am sure you are aware. I am not yet prepared to go there.

Richard Betts

I'm no expert in glaciology, just an old geologist, but my logic leads me to deduce that in glacial high altitude terrain, the importance of sublimation and ablation, moderated by humidity, solar irradiance and wind speed, may prevail as the dominant cause of wastage, rather than air temperature. Thus the topography of the local terrain, for example south facing icefields in the N hemisphere, insolation angle and topographically funnelled fierce winds may prevail as controls compared to ambient temperature.

Not sure I really understand those last 2 comments by Ronald Reagan and Lord Beaverbrook. Yes I think the world is probably going to get warmer as a result of ongoing emissions of greenhouse gases - I don't know how much warmer, and I don't know what the impacts will be, but I think it's worthwhile trying to find out. What the elected government of the day does about trying to stop it, or adapt to it, is their concern (and of course that of the voting public). My job is just to try and advise them on the possible consequences of different courses of action to the best of our current understanding, so they can make decisions which are as informed as possible. In many cases this does of course come down to hedging their bets. As I believe I have said before, if you don't like the policy, tell your MP not me!

Richard Betts

I would of thought it to be just as important to know what effects a cooler climate would have. Especially if it is the intention to try and force a stop to rising temperatures by Government policy. We wouldn't want to spend trillions trying to force an issue that we didn't know the outcome of, that just wouldn't be wise now would it.

@Richard Betts: "...was going to do under a warming climate..."

There you go again. ;-)

Lord Beaverbrook

Yes, it's all interlinked. If only we knew what ENSO was going to do under a warming climate, we'd be a long way towards being more confident in regional precip projections....!

http://wattsupwiththat.com/2011/07/28/al-gores-drowned-polar-bear-ait-source-under-investigation/
Well now; there's a thing!
Philip Jourdan's comment below the article is worth taking to heart!

Richard Betts

I don't want to interupt Geronimo but aren't the monsoons influeced by Enso conditions in the Pacific? Surely with the conditions being mostly positive in the last 30 years the monsoons will react in a specific manner but if the conditions move more neutral or mostly negative then the monsoons will react differently thus changing their influence on glaciers, snow fall etc

I still recomend starting a discussion rather than posting in unthreaded..

Jul 27, 2011 at 6:40 PM | geronimo

Thanks for an excellent question on glaciers - this is exactly the kind of thing I was hoping we could discuss here, as it's the kind of complex issue that gets simplified and misunderstood.

First, a clarification - did you really mean 8000 feet for the altitude at which "generally speaking temperatures never rise above zero"? That's not true, it can very often be well above zero Celcius at 8000 feet, you just need to go to the mountains in summer to check this!

However, that aside, your question is perfectly reasonable for a more general issue of high-altitude glaciers.

It's worth bearing in mind that even in places where the annual mean temperature can be sub-zero (such as over all of Greenland) that does not mean that there is no melting. Even a place with a mean summer temperature of -10C is likely to have a few days a year when the temperature is above zero and melt can occur. There is even occasional melt on Greenland during winter when a rare synoptic event brings warm air in.

But you focussed specifically on precipitation, and again that's a really good point. We do indeed expect a general increase in global average precipitation in a warming world. But again this doesn't mean an increase in precipitation in all places. More moisture in the atmosphere means a stronger hydrological cycle over the foothills of the Himalayas, but it does not necessarily mean more snow at altitude. It's the changes in atmospheric circulation that matter.

Glaciers over the western Himalayas are getting less snow and those over the east more (due to a change in the monsoon). Data from the western Himalaya show that seasonal mean, maximum and minimum temperatures have increased by 2, 2.8 and 1.8C, respectively since 1984. Of the 4 mountain ranges in the Western Himalayas, Pir Panjal, Shamshawari, Greater Himalaya and Karakoram, only the Karakoram shows a cooling trend (and here 1/3 of the glaciers are advancing, 1/3 static and 1/3 retreating). Regional snowfall has decreased, so the glaciers are in general losing mass.

But not all individual glaciers are retreating (despite what some people might claim) and the whole process is somewhat complex.

I'm glad you used the date of 2350 not the embarrassing 2035 error! However even with that correction in mind, I'm sure the AR4 discussion is a long way from being the last word on the subject. You can look forward to some more extensive discussion in AR5 - and hopefully the glaciologists will be all over it during the review process!

NASA satellite data from the years 2000 through 2011 show the Earth's atmosphere is allowing far more heat to be released into space than alarmist computer models have predicted, reports a new study in the peer-reviewed science journal Remote Sensing. The study indicates far less future global warming will occur than United Nations computer models have predicted, and supports prior studies indicating increases in atmospheric carbon dioxide trap far less heat than alarmists have claimed.

http://news.yahoo.com/nasa-data-blow-gaping-hold-global-warming-alarmism-192334971.html

This summer just keeps getting better and better.